Heat source used in calibrating a heat sensor



FIG. 1 is a side elevational view of a heat source used in calibrating a heat sensor, showing my new design, the opposite side being a mirror image thereof;

FIG. 2 is a top plan view thereof.

FIG. 3 is a bottom plan view thereof.

FIG. 4 is a front elevation view thereof.

FIG. 5 is a rear elevation view thereof. 

The ornamental design for a heat source used in calibrating a heat sensor, as shown and described. 